1. Field of the Invention
The present disclosure relates to an apparatus for generating a high frequency signal, and more particularly relates to an apparatus for generating a high power signal with reducing size of the apparatus.
2. Description of the Related Art
A very high frequency band, for example THz, in the limelight in recent has been required in various application fields such as an imaging or a wideband communication. Importance of a THz system has increased.
It is possible to achieve the THz system driven with small size, low cost and low power due to enhancement of performance of a semiconductor device. Additionally, it is difficult to manufacture the THz system in on-chip because a passive circuit such as a coupler has very great size, in a lower frequency band. However, the THz system can be realized in on-chip in a high frequency band because the passive circuit has small size according as a frequency gets higher.
Highest issue in a THz band is to manufacture a high power signal source. The higher an output power of a generated signal gets, the better a signal to noise SNR at a receiver side can be obtained. Hence, a high resolution system can be achieved. However, it is difficult to produce a generator for operating in the high frequency band. Accordingly, technologies capable of improving a performance such as an operation frequency, an output power, a phase noise, etc. of the generator have been actively studied.
It is difficult to produce the generator for operating in the high frequency band, but it is more difficult to obtain high output power. Since it is difficult to manufacture an amplifier, it is limited to increase the output power by using a power amplifier used in the low frequency band. Even if the power amplifier for generating a high power might be manufactured, energy efficiency is low because the power amplifier consumes very high DC power.
The Korean laid open patent No. 10-2014-0058742 (title: a wideband add-drop circuit for a microwave integrated circuit) discloses a technique for receiving two high frequency signals which have 180° phase difference and overlapping and cancelling the received high frequency signals. However, the patent does not disclose a technique for generating a signal having higher output power than the overlapped signal. Furthermore, the patent does not provide a technique for minimizing a size of an apparatus for generating a high frequency signal.